Three guys came two a small town and were looking for somewhere to sleep. They saw a house where it said "Room Available", so they asked the price and was told it was $10 per night per person. So they payed, got their keys and went to their rooms.

Later the owner came by and asked if there were any visitors, and he was told three guys had rented a room each. He asked how much they payed and was told $10 each. He said "Let's be nice to them, take $5 and give it back to them", so the clerk took $5 and walked towards the rooms thinking it would be hard to divide $5 on three guys, so he took $2 for him self and gave the visitors $1 each.

So now they'd payed $9 each, that's $27 total, plus the $2 the clerk stole becomes $29. Where's the last dollar?